Automatic welding systems for effecting a 360.degree. weld about either the exterior or interior of pipes are well known. Generally these systems will include a welding mechanism having a travelling carriage which will support a torch head and cause it to actually orbit around the exterior of the pipe where an exterior weld is to be made or in those instances where an interior weld is to be made, the travelling carriage will move about the inside of a pipe.
These known machines also include mechanism for causing the carriage to oscillate back and forth as it progresses over 360.degree. so that an oscillating path for the torch is effected and thereby provides for proper heating of the material and proper welding with only one 360.degree. sweep. Also, controls are provided for varying the arc gap of the torch head relative to the weld to provide for automatic voltage control. In addition, automatic wire feed rate controls are provided in TIG systems, the various relative motions all being programmed to provide for a high quality controlled weld.
While the above-described automatic welding systems are highly successful, they cannot readily be used for relatively small pipe welding operations; that is, small pipes that may vary in diameter from 1/2 inch to 3 inches and particularly they cannot be used for pipes that are already in place, where the surrounding pipe connections can block the entry of the welding mechanism.
As a consequence of the foregoing, it has been necessary to hand weld some of the smaller pipe sections and thus the advantage of consistency and proper weld quality realizable with automatic welding equipment is lost.
While it might be possible to automate some of the welding movements such as an orbiting of the weld torch head about the pipe without requiring too much space, there has never been available a full function automatic welding system for the small diameter pipes in in-place applications which provides for appropriate oscillation of the torch head across the weld path as it progresses about the pipe, nor has there been available any automatic system for providing other weld functions.